1. Field of the Invention
The present invention relates to a semiconductor device, a method of manufacturing a semiconductor device, and a substrate processing apparatus.
2. Description of the Related Art
To highly integrate metal-oxide-semiconductor field effect transistors (MOSFETs) and increase the performance of the MOSFETs, the use of a high-k/metal gate structure is considered, which is constituted by a gate insulating film made of a high permittivity insulating material (high-k material) and a gate electrode made of a metal. In the case of a p-channel metal-oxide semiconductor (PMOS) transistor, it is preferable that a gate electrode is made of a metal having a high work function of about 4.8 eV to 5.1 eV, and for example, it is considered that a gate electrode is made of a noble metal such as platinum (Pt).
Furthermore, in the case of a dynamic random access memory (DRAM), it is considered that a capacitor insulating film is in de of a high permittivity insulating material such as a hafnium dioxide (HfO2), a zirconium dioxide (ZrO2), a titanium dioxide (TiO2), a tantalum pentoxide (Ta2O5), and a niobium pentoxide (Nb2O5). In addition, a leak current of a capacitor part can be effectively reduced by forming a capacitor electrode using a metal having a high work function. Thus, when a capacitor insulating film is made of HfO2 or ZrO2 having a wide band gap, a capacitor electrode is made of a material such as a titanium nitride (TiN) having a work function of about 4.6 eV. In addition, when a capacitor insulating film is made of TiO2 or Nb2O5 having a narrow band gap, a capacitor electrode is made of a noble metal such as Pt having a high work function of about 5.1 eV.
However, if a metal film (for example, a gate electrode, a capacitor electrode, etc.) made of an expensive noble metal such as Pt, the manufacturing costs of a semiconductor device may be increased. In addition, it is difficult to form a thin film by using a noble metal such as Pt. It can be considered that another metal having a high work function such as nickel (Ni) or cobalt (Co) is used instead of a noble metal such as Pt. However, such a metal is easily oxidized, and if a metal film (a gate electrode or a capacitor electrode) is oxidized, the equivalent oxide thickness (EOT) of the metal film may be increased.